JEE Mains · Chemistry · STD 11 - 5. Thermodynamics and thermochemistry
The reaction of cyanamide, \(NH _{2} CN _{( s )}\) with oxygen was run in a bomb calorimeter and \(\Delta U\) was found to be \(-742.24\, kJ\, mol ^{-1}\). The magnitude of \(\Delta H _{298}\) for the reaction \(NH _{2} CN _{( s )}+\frac{3}{2} O _{2}( g ) \rightarrow N _{2( g )}+ O _{2}( g )+ H _{2} O _{(l)}\) is ............ \(kJ\). (Rounded off to the nearest integer) [Assume ideal gases and \(\left. R =8.314\, J\, mol ^{-1} K ^{-1}\right]\)
- A \(343\)
- B \(741\)
- C \(783\)
- D \(561\)
Answer & Solution
Correct Answer
(B) \(741\)
Step-by-step Solution
Detailed explanation
\(\Delta H =\Delta U +\Delta n _{ g } RT\) \(=-742.24+\frac{1}{2} \times \frac{8.314}{1000} \times 298\) \(=-741 kJ / mol\)
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